How about a feat for DnD 5e?
Light Armor Mastery
prerequisite: Proficiency with light armor
You dance like the wind in light armor, gaining the following benefits.
- Increase your dexterity or strength score by 1, to a maximum of 20
- Increase your movement speed by 10 feet
- When you take damage from a melee attack, you can disengage as a reaction.
Thoughts?
Throat Punch Games 
I would drop the Stat increase and change take damage to when attacked, after the attack is resolved. So you could disengaged when missed. I would also require you to be wearing light armor to use that reaction.
I like the disengaged when missed angle. as well as requiring the use of the light armor. I don’t think the stat power is too big, as all the other armor power up feats give the same ability increase.
Considering this one feats gives the same exact bonus as the swift feat, AND a +1 to an ability, AND the ability to disengage as a reaction I would say this is way overpowered.
And by the way, disengage doesn’t actually allow you to move. It just makes your movement for that turn not provoke attacks of opportunity. So unless you have a way to move on someone else’s turn that doesn’t also use your reaction, the last part is probably not what you meant to say. I’m guessing you meant “disengage AND move” which would make the feat even more ridiculously overpowered. That would be giving you an action and a move action (aka a whole turn besides the bonus action) as a reaction. At will.
I would say this is at least two and half feats all wrapped up in one. That all being said, I love the idea of a Light Armor Mastery feat.